SFS Annual Meeting

6/03/2024  |   13:30 - 13:45   |  Independence Ballroom A

Evaluating the Impact of Hydrologic Variability and Land Use on Stream Ecosystem Health in the Piedmont Region Land use and land cover change have strong impacts on aquatic metabolism in streams and rivers through changes in hydrologic regimes, light, nutrients, and other factors. However, efforts to quantify these relationships are difficult because of the disparate and convolved impact multiple changes can have on metabolism. This study utilizes a comprehensive dataset of stream metabolism modeled from dissolved oxygen from 2008 to 2021 across 11 sites in the Piedmont region of the U.S. southeast to investigate the response of aquatic ecosystems to fluctuations in hydrology, using resistance and resilience as key indicators. Resistance is defined as the degree to which production and respiration rates are altered by flow events, while resilience measures the time required for these rates to revert to their baseline levels following such events. The analysis further incorporates watershed land use characteristics and a riparian vegetation index to categorize each site, providing insights into the interplay between watershed characteristics and stream ecosystem health. This study is expected to reveal the dynamic responses of stream metabolism to fluctuating hydrologic conditions, with a particular focus on how varying watershed characteristics and the presence of riparian vegetation might influence these interactions.

Deandre Presswood (Primary Presenter/Author), Georgia State University, deandrepresswood@gmail.com;

Sarah H. Ledford (Co-Presenter/Co-Author), Georgia State University, sledford@gsu.edu;

Marie J. Kurz (Co-Presenter/Co-Author), Oak Ridge National Laboratory , kurzmj@ornl.gov;

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6/03/2024  |   13:45 - 14:00   |  Independence Ballroom A

Variability in fluorescent dissolved organic matter concentrations across monthly to seasonal time scales in urban waters Continuous and frequent monitoring of dissolved organic matter (DOM) in urban streams is vital for understanding its variability across various time scales. Therefore, quantifying the magnitude of DOM fluctuations across multiple temporal scales in urban aquatic ecosystems with diverse hydrology and water sources is needed. From 2020-2023, we used high-frequency in situ fluorescent DOM (fDOM) sensors and time-series modeling to explore dominant time scales of fDOM concentration variability and environmental predictors in two urban waterways, an estuarine tidal creek [Little River (LR)] and an inland tidal creek [Coral Gables (CG) Canal]in Miami, FL (USA). Both canals provide an ideal setting for studying the ongoing perturbation caused by anthropogenic influences, tides, and additional environmental factors, including subtropical wet-dry seasonality. Our goal was to identify the environmental and anthropogenic factors that predict fDOM dynamics on daily to seasonal time scales in urban streams. We found higher fDOM levels in LR (98.37 ± 0.16, QSU) compared to CG (26.73 ± 0.04, QSU). At both sites, fDOM was out-of-phase with salinity, recurring in an eight-month to twelve-month cycle. This pattern indicated a consistent dilution effect on fDOM concentrations produced by tides throughout the year. However, LR had greater tidal influence than CG, as supported by a negative correlation with salinity (-0.83, psu) and conductivity (-0.83, uS cm-1). Our research improves our understanding of fDOM variations in coastal urban aquatic ecosystems, explaining different timescales and drivers of biogeochemical changes.

Liz Ortiz (Primary Presenter/Author), Florida International University, lorti080@fiu.edu;

John Kominoski (Co-Presenter/Co-Author), Florida International University, jkominos@fiu.edu;

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6/03/2024  |   14:00 - 14:15   |  Independence Ballroom A

NUTRIENT AND ORGANIC MATTER DYNAMICS IN STORMWATER PONDS WITHIN MASTERPLANNED RESIDENTIAL COMMUNITIES Increasing stormwater runoff is an environmental consequence of urbanization. Increasing stormwater runoff necessitates the development of stormwater control measures to protect downstream ecosystems. Stormwater wet ponds (SWPs) are a commonly implemented stormwater control measure typically designed for flood control. These artificial aquatic ecosystems are also expected to retain/remove nutrients associated with urban runoff. To understand the efficacy of SWP nutrient removal and ecosystem functioning, we are investigating nutrient (nitrogen, phosphorus) and organic matter (OM) dynamics in two master-planned residential communities in central and southwest Florida. We are sampling 19 ponds monthly for dissolved nitrogen, phosphorus, and organic carbon (DOC) concentrations, and are assessing the spectral characteristics of dissolved OM to establish baseline chemical conditions of SWPs. Preliminary results suggest high concentrations of DOC (range: 4.4-38.0 mg/L) with a highly humic composition (Humification Index: 0.71-0.92). Total nitrogen averaged 0.44 (86% as organic nitrogen) and 1.1 (60% as organic nitrogen) mgN/L in central and southwest FL communities, respectively. Algal biomass (as chla) samples collected from one community reveal considerable among-pond variability (4.6-110 ug/L), despite common management. These differences within and among communities suggest the importance of management practices for water quality. Moving forward, we will relate water chemistry with socioeconomic factors (property values, social perceptions, management actions). Further, we will link pond metabolism and nutrient cycling with characteristics of algal and bacterial communities. Ultimately, these ecological responses will be connected to social perceptions and behaviors to identify how human actions on the land affect functioning of these ubiquitous artificial aquatic ecosystems.

Alexander Reisinger (Primary Presenter/Author), University of Florida, reisingera@ufl.edu;

Shuo Chen (Co-Presenter/Co-Author), University of Georgia; University of Florida, schen83@crimson.ua.edu;

Michelle Atkinson (Co-Presenter/Co-Author), University of Florida, michelleatkinson@ufl.edu;

Eban Bean (Co-Presenter/Co-Author), University of Florida, ezbean@ufl.edu;

Basil Iannone (Co-Presenter/Co-Author), University of Florida, biannone@ufl.edu;

H. Dail Laughinghouse (Co-Presenter/Co-Author), University of Florida, hlaughinghouse@ufl.edu;

Forrest Lefler (Co-Presenter/Co-Author), University of Florida, flefler@uf.edu;

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6/03/2024  |   14:15 - 14:30   |  Independence Ballroom A

WHEN PONDS FLOW: TESTING THE BIOLOGICAL EFFECT OF STORMWATER POND DISCHARGE ON RECEIVING STREAMS Stormwater ponds (SWPs) are built to protect downstream ecosystems, but support distinct planktonic communities, produce bioavailable forms of carbon and nutrients, and can export these microbes and resources downstream following storms. We tested the potential effects of SWP discharge on the planktonic community and ecosystem functioning of a receiving stream by experimentally combining SWP water and stream water across a pond:stream water gradient (six treatments spanning 0-100% pond water plus two tap water-only controls) in recirculating stream mesocosms. We sampled for water chemistry, microbial assemblage (16S rRNA metabarcoding), bacterial abundance (16S rRNA dPCR) and measured gas fluxes (carbon dioxide, methane) immediately after filling mesocosms (T0) and after five days of incubation (T1). After T1, we added a nutrient spike to measure nutrient (ammonium, nitrate, phosphate) uptake and collected nutrient samples the next day (T2). Throughout the incubation, sondes in each stream logged dissolved oxygen, temperature, pH, ORP, and conductivity (10 min resolution). Preliminary results show that after 5 days, bacterial abundance increased with increasing pond water until pond water became the majority (60% pond:stream), after which bacterial abundance decreased. Significant nutrient uptake was detected for ammonium (not nitrate or phosphate), and uptake rates increased with pond additions, plateauing at ~50% pond water addition. We predict that increasing fractions of pond water will increase the relative abundance of pond-associated taxa that persist by T1. This study illustrates the strong yet invisible impact stormwater ponds can have on downstream receiving waters and highlights potential parameters/metrics for future monitoring.

Audrey Goeckner (Primary Presenter/Author), University of Florida, agoeckner@ufl.edu;

Amanda Subalusky (Co-Presenter/Co-Author), University of Florida, asubalusky@ufl.edu;

Christopher Dutton (Co-Presenter/Co-Author), University of Florida, duttonc@ufl.edu;

Forrest Lefler (Co-Presenter/Co-Author), University of Florida, flefler@uf.edu;

H. Dail Laughinghouse (Co-Presenter/Co-Author), University of Florida, hlaughinghouse@ufl.edu;

Alexander Reisinger (Co-Presenter/Co-Author), University of Florida, reisingera@ufl.edu;

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